Photolysis of CH3C(O)CH3 at 248 and 266 nm: pressure and temperature dependent overall quantum yields

Khamaganov, Victor G.; Karunanandan, Rosalin; Horowitz, A.; Dillon, Terry J.; Crowley, John N.

doi:10.1039/b904130c

Cited by 14 publications

(26 citation statements)

References 32 publications

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“…This observation is in accord (regarding the pressure effect) with our previous work on acetone photolysis quantum yields [6,26]. The literature concerning the thermal dissociation of CH 3 CO was reviewed in our previous publication [26] and is not repeated here.…”

Section: -Nm Photolysis Of Ch 3 C(o)chsupporting

confidence: 90%

“…To measure the rate coefÞcient for the reaction of CH 3 CO with Br 2 , we made use of the fact that acetone photolysis at 266 nm (R1) results in formation of one CH 3 and one CH 3 CO radical. Our previous studies [6,26] have showed that at 60 Torr of N 2 , both the overall CH 3 C(O)CH 3 photodissociation quantum yield and the yield of CH 3 are close to unity, and that negligible amounts of the CH 3 CO formed decompose thermally to CH 3 + CO. The rate expression for Br atom formation is then…”

Section: Ch 3 Co + Br 2 (K 3 )mentioning

confidence: 93%

“…1) have been described previously [6,9], and only a brief summary is given here. The central component of the experimental setup is a 500-cm 3 , thermostated (224-358 K), cylindrical photoreactor/RF cell constructed of quartz.…”

Section: Methodsmentioning

confidence: 99%

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Rate coefficients for the reactions CH₃ + Br₂ (224–358 K), CH₃CO + Br₂ (228 and 298 K), and Cl + Br₂ (228 and 298 K)

Khamaganov

Crowley

2010

Int J of Chemical Kinetics

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Rate coefficients for the reactions of CH 3 + Br 2 (k 2 ), CH 3 CO + Br 2 (k 3 ), and Cl + Br 2 (k 5 ) were measured using the laser-pulsed photolysis method combined with detection of the product Br atoms using resonance fluorescence. For the reactions involving organic radicals, the rate coefficients were observed to increase with decreasing temperature and within the temperature range explored, were adequately described by Arrhenius-like expressions: k 2 (224-358 K) = 1.83 × 10 −11 exp(252/T) and k 3 (228-298 K) = 2.92 × 10 −11 exp(361/T) cm 3 molecule −1 s 1 . The total, temperature-independent uncertainty for each reaction (including possible systematic errors in Br 2 concentration measurement) was estimated as ∼7% for k 2 and 10% for k 3 . Accurate data on k 5 was obtained at 298 K, with a value of 1.88 × 10 −10 cm 3 molecule −1 s −1 obtained (with an associated error of 6%). A limited data set at 228 K suggests that k 5 is, within experimental uncertainty, independent of temperature. C 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: [575][576][577][578][579][580][581][582][583][584][585] 2010

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Section: -Nm Photolysis Of Ch 3 C(o)chsupporting

confidence: 90%

Section: Ch 3 Co + Br 2 (K 3 )mentioning

confidence: 93%

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Rate coefficients for the reactions CH₃ + Br₂ (224–358 K), CH₃CO + Br₂ (228 and 298 K), and Cl + Br₂ (228 and 298 K)

Khamaganov

Crowley

2010

Int J of Chemical Kinetics

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“…Photolysis of COCl 2 generates Cl atoms with a quantum yield of 2. 23,24 COCl 2 + hn (248 nm) -2Cl + CO (R7)…”

Section: Experimental Approachmentioning

confidence: 99%

Pressure dependent OH yields in the reactions of CH3CO and HOCH2CO with O2

Groß

Dillon

Crowley

2014

Phys. Chem. Chem. Phys.

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OH-formation in the reactions of CH3CO (R1) and HOCH2CO (R4) with O2 was studied in He, N2 and air (27 to 400 mbar) using OH-detection by laser induced fluorescence (LIF). 248 nm laser photolysis of COCl2 in the presence of CH3CHO or HOCH2CHO was used as source of the acyl radicals CH3CO and HOCH2CO. The LIF-system was calibrated in back-to-back experiments by the 248 nm laser photolysis of H2O2 as OH radical precursor. A straight-forward analytical expression was used to derive OH yields (α) for both reactions. A Stern-Volmer-analysis results in α1b(-1)(N2) = 1 + (9.4 ± 1.7) × 10(-18) cm(3) molecule(-1) × [M], α1b(-1)(He) = 1 + (3.6 ± 0.6) × 10(-18) cm(3) molecule(-1) × [M] and α4b(-1)(N2) = 1 + (1.85 ± 0.38) × 10(-18) cm(3) molecule(-1) × [M]. Our results for CH3CO are compared to the previous (divergent) literature values whilst that for HOCH2CO, for which no previous data were available, provide some insight into the factors controlling the yield of OH in these reactions.

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“…ref. 42 and references therein). The presented data are averages of two replicates, thus no errors are given with them.…”

Section: Photolysis Products and Mechanismmentioning

confidence: 99%

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH₃C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C₂H₅F)

Song

Zügner

et al. 2015

J. Phys. Chem. A

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ABSTRACT:The direct reaction kinetic method of low pressure fast discharge flow (DF) with resonance fluorescence monitoring of OH (RF) has been applied to determine rate coefficients for the overall reactions OH + C 2 H 5 F (EtF) (1) and OH + CH 3 C(O)F (AcF) (2). Acetyl fluoride reacts slowly with the hydroxyl radical, the rate coefficient at laboratory temperature is k2 (300 K) = (0.74 ± 0.05) × 10 -14 cm 3 molecule -1 s -1 (given with 2σ statistical uncertainty). The temperature dependence of the reaction does not obey the Arrhenius law and it is described well by the two-exponential rate expression of k 2 (300-410 K) = 3.60 × 10 -3 exp(-10500 / T) + 1.56 × 10 -13 exp(-910 / T) cm 3 molecule -1 s -1 . The rate coefficient of k 1 = (1.90 ± 0.19) × 10 -13 cm 3 molecule -1 s -1 has been determined for the EtF-reaction at room temperature (T = 298 K).Microscopic mechanisms for the OH + CH 3 C(O)F reaction have also been studied theoretically using the ab initio CBS-QB3 an G4 methods. Variational transition state theory was employed to obtain rate coefficients for the OH + CH 3 C(O)F reaction as a function of temperature on the basis of the ab initio data. The calculated rate coefficients are in good agreement with the experimental data. It is revealed that the reaction takes place predominantly via the indirect H-abstraction mechanism involving H-bonded prereactive complexes and forming the nascent products of H 2 O and the CH 2 CFO radical. The nonArrhenius behavior of the rate coefficient at temperatures below 500 K is ascribed to the significant tunneling effect of the in-the-plane H-abstraction dynamic bottleneck. The production of FC(O)OH + CH 3 via the addition/elimination mechanism is hardly competitive due to the significant barriers along the reaction routes.Photochemical experiments of AcF were performed at 248 nm by using exciplex lasers. The total photodissociation quantum yield for CH 3 C(O)F has been found significantly less than unity; among the primary photochemical processes, C-C bond cleavage is by far dominating compared with CO-elimination. The absorption spectrum of AcF has also been determined displaying a strong blue shift compared with the spectra of aliphatic carbonyls.Consequences of the results on atmospheric chemistry have been discussed.3

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Photolysis of CH3C(O)CH3 at 248 and 266 nm: pressure and temperature dependent overall quantum yields

Cited by 14 publications

References 32 publications

Rate coefficients for the reactions CH₃ + Br₂ (224–358 K), CH₃CO + Br₂ (228 and 298 K), and Cl + Br₂ (228 and 298 K)

Rate coefficients for the reactions CH₃ + Br₂ (224–358 K), CH₃CO + Br₂ (228 and 298 K), and Cl + Br₂ (228 and 298 K)

Pressure dependent OH yields in the reactions of CH3CO and HOCH2CO with O2

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH₃C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C₂H₅F)

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Photolysis of CH3C(O)CH3 at 248 and 266 nm: pressure and temperature dependent overall quantum yields

Cited by 14 publications

References 32 publications

Rate coefficients for the reactions CH3 + Br2 (224–358 K), CH3CO + Br2 (228 and 298 K), and Cl + Br2 (228 and 298 K)

Rate coefficients for the reactions CH3 + Br2 (224–358 K), CH3CO + Br2 (228 and 298 K), and Cl + Br2 (228 and 298 K)

Pressure dependent OH yields in the reactions of CH3CO and HOCH2CO with O2

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH3C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C2H5F)

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Rate coefficients for the reactions CH₃ + Br₂ (224–358 K), CH₃CO + Br₂ (228 and 298 K), and Cl + Br₂ (228 and 298 K)

Rate coefficients for the reactions CH₃ + Br₂ (224–358 K), CH₃CO + Br₂ (228 and 298 K), and Cl + Br₂ (228 and 298 K)

Experimental and Theoretical Study on the OH-Reaction Kinetics and Photochemistry of Acetyl Fluoride (CH₃C(O)F), an Atmospheric Degradation Intermediate of HFC-161 (C₂H₅F)